The goal of the proposed two-year study (written in response to PA-06-284) is to test a quantitative model of temperament that utilizes composites to describe and predict stability and change in individual differences from 2-6 years of age. We will analyze the first two phases of data from the NICHD Study of Early Child Care and Youth Development, a multi-site longitudinal study that began in 1991 with an ethnically and socio- economically diverse sample of 1,364 youth, their parents, and childcare providers. The study includes thorough measurement of a wide range of child psychological constructs spanning cognitive, language, and social-emotional development, as well as measures of home, childcare, and school environments. We will focus on three major dimensions of temperament: effortful control (e.g., attention, low-intensity pleasure), surgency (e.g., activity, high-intensity pleasure), and negative affectivity (e.g., fear, irritability). Using confirmatory factor analysis, we will derive composites that are internally consistent and robust in their measurement structure from 2 to 6 years of age, and that show predictive validity with respect to cognitive, achievement, and social-emotional outcomes. We also will employ rigorous longitudinal analysis methods including latent growth curve and growth mixture modeling to examine developmental trajectories. In addition to disseminating the results, the measurement model will become part of the public-use dataset. We will test three sets of hypotheses: 1. We anticipate finding evidence for a three-dimension measurement model (effortful control, negative affectivity, and surgency). 2. Individual differences in these dimensions of temperament will be moderately stable over time, though we also will identify and be able to predict patterns of change. 3. The best cognitive and social-emotional outcomes will be correlated with higher effortful control and lower negative affectivity, whereas links with surgency will be more mixed. We also anticipate finding different effects on these outcomes arising from temperament-by-environment interactions. These findings will inform practitioners about ways in which the fit between children's attributes and methods of intervention or instruction can be ascertained. The research also will provide information for professionals working to improve the parenting environments of children who show challenging behaviors that interfere with their social-emotional development and learning. [unreadable] [unreadable] [unreadable] [unreadable]